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UV Light For HVAC

Had a customer today inquire about adding UV lights to his duct work. Anyone have some good information as to the effectiveness of the lights ? What models are worthwhile? I do recall you have to be careful where you install them, flex connectors and filter media cannot withstand it. Should you have one in the supply and return ? Can all evaporator pans now a days tolerate it ?

IMO, if everything is well sealed..there isn't anything in the duct system that needs uv lights.

that said...I replaced a ductboard supply plenum that had uv light.
everywhere the uv light could reach...no mold. where it didn't reach...mold.
so they do stop growth they reach.
if you look at the picture,
on the sides of the plenum..close to uv light...no mold. further on, where light
couldn't reach...mold.
the question to me alway was...what is causing mold?

in this case it was no seal at duct takeoffs at the plenum &
poor seal @ plenums to equipment.
condensation caused by hot attic air touching metal take offs
caused moisture inside (and outside) of plenum.
ended up changing most of the ductwork too, as mold had grown
inside flex.
plenums were changed to sheet metal externally insulated as per
homeowner concerns.

hope this helps.

The cure of the part should not be attempted without the cure of the whole. ~Plato

Wow the UV light subject is defiantly a frustrating issue. Seems like to there is no consistency to anything regarding UV lights and everyone seems to have a different option. At any rate I was ultimately referred to RGF Guardian Air HVAC Cell and REME HVAC Cell. I was offered a substantial discount on the REME for my house so that I can experience it and then hopefully push the sales of them. Seems like this thing is adding peroxide, plasma or whatever to the air, which im not crazy about. Anyone else use these ?

Gentlemen UVGI lamps are an excellent selection for surface irradiation. But a bad selection for IAQ. Their simply isn't enough time to deactivate a biologic moving at 500 fpm. If installed correctly they will do a good job of keeping the bio slime off of the coil which will maintain the heat transfer efficiency at the evap coil.

The premise of ventilation is that the OA is clean or of sufficient quality to be used for dilution. Traditional ventilation is somewhat being threatened by the fact that the EPA is changing the requirements for outdoor air quality which is creating non-attainment zones in what is now becoming a significant portion of the country. That means that buildings in those areas will need to clean up the OA before they bring it into the building.www.genesisair.com
Genesis Air Inc.

Gentlemen UVGI lamps are an excellent selection for surface irradiation. But a bad selection for IAQ. Their simply isn't enough time to deactivate a biologic moving at 500 fpm. If installed correctly they will do a good job of keeping the bio slime off of the coil which will maintain the heat transfer efficiency at the evap coil.

Additionally, if you do install one, insure that EVERY material within about 3 feet of the light is UV rated.

Any organic material that is high %RH for +24 hours has a high potiential for mold growth. Mold spores and organic dust are everywhere. A couple hours of drying out the ducts every 12 hours could stop mold spore from growing. A/c ducts in attics with moisture saturated cooling coils will keep the ducts near saturated for days on end. Completely drying out the ducts by operating the fan a couple hours twice a day stops mold. Fans in the "on" mode 24/7 are most likely to be clear of mold. There are other problems.
Also ducts in attics during cold weather also have mold potiential from condensation on the ducts when the duct surface is near the dew point of interior air dew point. Again operating the fan several hours each day will dry these surfaces and prevent mold spore germination.
Good indoor air quality requires fresh air change when occupied. An air change in 4-5 hours is usually adequate when occupied.
Air filtering to keep the equipment clean. Merv +11 is suggested for inside and fresh make-up ventilation.
Maintaining <50%RH throughout the inside of a home avoids mold and dust mites. Air ducts spend many hours with 80%-near 100%RH during cooling hours. Several hours everyday of <50%RH everyday will reduce mold/bacteria to minimable level.
In green grass climates, a whole house ventilating dehumidifier like the Ultra-Aire supplys fresh filtered air, blends the filtered dry air with filtered house air, circulated the conditioned air throughout the home via the a/c ducts. This procces maintains <50%RH throughout the all of the equipment.
In most cases the 100 watt fan of the dehumidifier can operate 24/7 which keeps everything dry during the "off" cycle. The real long term effects of UV lites on sensitive occupants is unknown.
Fresh filtered air, keep every dry when not in use, and low circulation is effective for indoor air quality.
Regards TB

We always used uv resources equipment in the air handlers when I worked in mfg.. as said before keep all wireing you can away from the area, run the wireing in conduit or shield it some way and if you have to use zip ties make sure they are uv rated. they can also help design a system

I have found mold growth in units,with the customers reporting feeling very weak after leaving the home each day. We tried a duct cleaning along with a UV light but after 3 months the problem got better but didn't go away. Eventually we had to replace the unit and ductwork to eliminate the mold permanently. I believe UV can inhibit new growth and odor but does very little if anything for ridding existing mold inside the ductwork and coil.